Quick question, I was thinking about doing the o2 sim and Im wondering what the before and after gas mileage was like. I know that once I changed my o2 sensors I got a fairly large jump in mpgs.
Do the mpgs go up, down, or stay the same?

 

The o2sim is suppose to trick the ecu. Your MPG should stay the same. The 2 rear o2 sensors don't effect your MPG.

 

o2 sim + headers = better mileage

Your gas mileage will only change if your o2 sensors currently are not working, which would cause the engine to run too rich (and thus inefficiently). One question though: why would you want to simulate o2 sensors if they are still there? (realize, the majority of people using sims need them bc of a header install, without which they would throw a code)

And more questions: do you have any codes? what is your current gas mileage? (and if you don't know the answer to the last question, how would you notice any change in your mileage...?)

 

Currently my gas mileage varies between 18-20 depending on how aggressively i drive. I am currently getting a p0430 code, however i am looking to replace the troubled precat.
I was more curious because I am thinking about getting a set of cattman headers and know that they eliminate the precats and therefore I'd imagine that'd I'd always have a p0430 and p0420 codes.

 

I definitely recommend getting the headers. You will not be disappointed. Given your situation, I'd say it wouldn't hurt to get an o2 sim.

 

The rear O2 sensors exist only for emissions to make sure the cat converters are still in place and working. They have no effect, whether working or throwing a code, on your gas mileage. The main gas mileage gain that normally includes using O2 sims is installing headers. After the headers are installed, you must either reinstall the rear sensors and use spark plug defoulers to fool them or use an O2 simulator if you wish to avoid a code.

Simulating the rear sensors or using spark plug defoulers will get rid of the 0430/0420 codes. Keeping them plugged in after simulating will keep you from getting the 0138/0158 codes.

 

1. If your precat is bad, get a new one.

2. If your O2 sensor is bad, get a new one.

3. If your looking for a slight increase in power and exhaust tone, get headers.

4. If you have a CEL after the header instal even with good O2's get an O2 sim.

 

Most wouldn't call a 10-15% gain throughout pretty much the entire power band a slight increase, but I guess that's relative to what you're comparing it to.

 

Yeah I would say get the headers for the power increase...also what state are you in Im in Cali and they be a ***** when it comes to smog waiting later on this year to buy some headers probably in June from Cattman but install in Dec...after my smog so I got time to come up with a solution to pass the sniffer out here....

 

Comparing it to a 125 shot of teh juice...

 

A 125 shot through stock manifolds/precats doesn't seem too smart, plus not exactly comparable with the constant benefits of headers. Plus for a NA mod, it's the single largest difference mod there is. Probably the 2nd best dollar per power NA mod there is behind IM spacers on the 3.5 or Y-pipe only on the 3.0.

 

The sarcasm bus missed your stop.